crossover building?

Not quite. What you have there is effectively still a second order low pass filter (but not quite because your added cap is doing high pass work, so in theory it is working like a bass blocker. This is not, however, the way to design what you're wanting.). At high frequencies, capacitors become shorted and inductors create an open circuit. At low frequencies, inductors create a short and capacitors create an open circuit. This is why if you look at your high pass filter, you have a capacitor and a parallel inductor and on the low pass originally was a series inductor and a parallel capacitor. What you'll end up with even if you switch out the inductor is still just a low pass filter, albeit 3rd order. What you're trying to make is a bandpass filter which is instead a parallel inductor and capacitor or a series inductor or capacitor (the latter is more appropriate for high-fi audio as putting anything in series with the driver introduces its effects to the resulting signal. If you have very high quality caps and low DCR inductors, then the series approach works fine). A combination of both types creates a higher order filter. Hope that helped some. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

well said.